ML18114A243

Response to Letter 1/30/1978, Information on Steam Generator Is Provided

ML18114A243
Person / Time
Site:	Saint Lucie
Issue date:	02/21/1978
From:	Robert E. Uhrig Florida Power & Light Co
To:	Stello V Office of Nuclear Reactor Regulation
References
L-78-61
Download: ML18114A243 (7)

Text

I REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

DISTRIBUTION FOR INCOMING MATERIAL 50-335 REC:

STELLO V NRC ORG:

UHRIG R E

FL PWR 8c LIGHT DOCDATE: 02f21/78 DATE RCVD: 02f24f78 DOCTYPE:

LETTER NOTARIZED:

YES

SUBJECT:

RESPONSE

TO NRC"S LTR DTD Oif30f78... FURNISHING INFO ON UNIT 1

STEAM GENERATORS.

COPIES RECEIVED LTR 3 ENCL 0 APPLICANT"S PLANT NAME: ST LUCIE Ni REVIEWER INITIAL:

XJM DISTRIBUTOR INITIAL:

DISTRIBUTION OF THIS MATERIAL IS. AS FOLLOWS +++++>>++>>>>+>>>>

RESPONSES TO STEAM GENERATOR QUESTIONNARE'DISTRIBUTION CODE A023)

FOR ACTION:

INTERNAL:

EXTERNAL:

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CONTROL NBR:

780580015 THE END

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FLORIDAPOWER & LIGHT COMPANY February 21, 1978 L-78-61 Office of Nuclear Reactor Regulation Attention:

Mr. Victor Stello, Director Division of Operating, Reactors U. S. Nuclear Regulatory Commission Washington, D.

C.

20555

Dear Mr. Stello:

Re:

St. Lucie Unit 1 Docket No.

50-335 STEAM GENERATOR INFORMATION

.. XYi COhLA(ISS lON bi@ %atlatl The following information on the St. Lucie Unit ~s cap generators is provided in response to your letter of>

January 30, 1978:

St. Lucie Unit 1 is scheduled for its first refueling outage around the first of April, 1978.

A steam generator inspection has been planned for this outage and will include some in-spection of the tube support plates for possible cracking.

The inspection program was developed in consultation with Combustion Engineering and is based on the findings at Millstone Unit 2.

This inspection will determine if any problems now exist with the steam generator upper horizontal drilled tube support plates.

After reviewing St. Lucie's history we find that chloride intrusion has been very limited and chloride exposure has been significantly less than that reported for Millstone Unit

2. It has been shown in the laboratory that chlorides are definitely implicated in the denting process and it is believed that'ood chemistry will minimize denting.

This is supported by recent steam generator inspections at Ft. Calhoun and Calvert Cliffs where there is good chemistry and the absence of denting.

Therefore, we believe that St.'ucie Unit 1 is free of denting, or at worst, that the denting phenomenon may be in an incipient stage.

Thus, it is concluded that signifi-cant support plate cracking does not exist because such crack-.

ing results from stresses created only when extensive denting is present.

Florida Power 6 Light Company has concluded that operation of St. Lucie Unit 1 will not create undue risk to the health and safety of the public.

This conclusion resulted from the re-view and consideration of the following information.

7gO5800 i5 PEOPLE... SERVING PEOPLE

(1)

St. Lucie is a relatively new plant which has operated with good secondary water chemistry (i.e., very limited chloride ingress)

This supports our contention that denting is not

present, or in the unlikely event that it has

started, that it has not progressed signifi-cantly.

(2)

The unit will only operate a short while before it will undergo a steam generator inspection (Inspection tentatively planned for April, 1978).

(3)

St. Lucie's total operating interval is consi-dered to be conservatively bounded by the Millstone Unit 2 experience (i.e., Millstone has operated longer than St. Lucie and has had greater chloride intrusion).

(4)

Industry research and field experience have demonstrated that extensive denting and support plate cracking eventually produce steam generator tube leaking.

Furthermore, these leaks (in inconel tubes) develop and propagate very slowly, thus enabling safe and orderly shutdown of the units.

(5)

St. Lucie has not had. any steam generator tube leaks.

In summary, we are keeping up to date with steam generator related activities within the industry, so we are familiar with the types of corrective action which could be imple-mented if the need arises.

In the unlikely event, that. ab-normal findings result from the planned steam generator inspections, they will be evaluated jointly with the vendor to develop appropriate corrective action.

Very truly yours, Robert E. Uhrig Vice President, REU/MAS/RSA/bab cc:

Mr. Games P. O'Reilly, Region II Harold F. Reis, Esquire Mr. Pete B. Erickson

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ss Robert E. Uhrig, being first duly sworn, deposes and says:

That he is a Vice President of Florida Power 6 Light Company, the Licensee herein; That he has executed the foregoing document; that, the state-ments made in this said document are true and correct to the best of his knowledge, information, and belief, and that he is authorized to execute the document on behalf of said Licensee.

Robert E. Uhrig Subscribed and sworn to before me this

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day of 19 )Z NOTARY PUBLIC, in and for the County of Dade, State of Florida NOTARY FUCuC STAN OF fLORfDA et LRRQC MY CC).t'8ISGIOl4 f>;f'IRc3 AUGUST 24, 19C>

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